Water is a critical component of natural gas development; not only is water used in the process of hydraulic fracturing but ensuring that water infrastructure and supplies near drilling sites are not impacted by exploration and extraction activities is also important to industry.
Before any wells are even drilled, extensive surveillance, monitoring and analysis of water supplies is performed to ensure a minimal impact of operations on the local community. Fresh ground water monitoring is always applied if specifically requested for permit obligations. As a normal part of the extraction and production process companies work closely with local communities to ensure, through on-going community outreach programs, that development activities do not negatively impact the community’s safety, economy or environment. Transparency on water issues related to exploration and extraction ensures open discussion about environmental protection and risk management, and the potential benefits of shale development in Europe.
Hydraulic fracturing used for the extraction of unconventional gas occurs far below the deepest potable groundwater aquifers; deposits are located 1-3 kilometers below the aquifers and all responsible operators implement a series of precautionary measures to ensure risk is removed. Additionally, fresh water monitoring is conducted before and after operations to ensure that there has been no impact.
Nature also limits the risk of impacts on groundwater. Multiple layers of impermeable rock between the water supply and gas-bearing rock ensure that fracks do not extend into groundwater aquifers.
Key to groundwater protection is proper well-design. To ensure protection of groundwater supplies when a natural gas well is drilled, multiple layers of steel and cement casing line the wellbore to create several impermeable barriers; these are then tested for leak-tightness prior to operation to ensure integrity.
The surface site is also designed to isolate groundwater from drilling and production operations. When the well is decommissioned, the entire wellbore is filled with cement and sealed just below the surface to provide long-term protection to both soil and groundwater aquifers.
At the European and national level, there is a robust regime in place for regulating chemicals used in fracturing fluid under the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) Regulation. While there is no specific identifier on REACH forms for ‘hydraulic fracturing’, service providers have been using the ‘oil and gas extraction’ category; many exploration and production companies active in European unconventional gas exploration already disclose this information on their company website to ensure transparency.
In the U.S., where commercial unconventional gas extraction is currently underway on a massive scale, studies by the Ground Water Protection Council and the Environmental Protection Agency have shown that here have been no confirmed incidents of groundwater contamination from hydraulic fracturing. Where there have been a small number of cases of water contamination, regulators have attributed these incidents to poor well construction or surface activities, rather than the specific hydraulic fracturing process.
The one million wells globally that have been completed safely using hydraulic fracturing demonstrate that the risks are manageable and that the extensive regulations and industry best practices already in place are effective. Industry has established vigorous safety standards and processes for its unconventional gas exploration and extraction operations and continues to monitor and manage risks daily to ensure the on-going safety of its operations, employees and local communities.
The amount of freshwater required for conducting the drilling and hydraulic fracturing process in a typical horizontal unconventional gas well in Europe is usually the equivalent of three to six Olympic-size (50 meters by 25 meters) swimming pools. This includes 2,500-5,000 cubic meters to drill the well and 7,500-15,000 cubic meters to perform a multi-stage hydraulic fracturing process, depending on the subsurface geology.
The water used in hydraulic fracturing typically comes from surface or groundwater sources. Prior to drilling a well, an evaluation of supply water is performed which includes consideration of volume and water quality requirements, regulatory and physical availability, competing uses, proximity, means of transport and characteristics of the geologic formation to be fractured; a source of water is then selected based on these factors and permits are applied for under applicable regulations.
The use of water in unconventional gas development is only required for a short period during development and is not a long-term requirement. The hydraulic fracturing process itself uses a significantly smaller amount of water compared to other industrial and recreational uses; coal mining, for example, requires two to four times more water per unit of energy produced whilst certain agricultural based biofuels, such as corn based ethanol, require 80 to 12,000 times more water per unit of energy produced. In the United States, where shale gas development is prevalent, water used for shale gas development in 2010 represented only about 0.02 per cent of total water used in the country.
During unconventional gas development, typically 10 per cent to 70 per cent of the water used is recoverable in the first two to three weeks, depending on the geology of the shale formation. Recovered water may contain suspended clay particles, dissolved inorganic components, organic compounds from the fracturing fluid and/or sand and silt particles from the shale.
Various treatment technologies allow the produced water to be reused for subsequent hydraulic fracturing operations and other industrial uses, or to be disposed. After separating the wastewater and natural gas, water can either be stored or recycled at the surface. In Europe, if no recycling occurs, the solid and liquid waste are stored temporarily in sealed containers, and then shipped to licensed water processing facilities for treatment and disposal according to the permit procedures and applicable regulations.
In Germany, for example, the current practice of pre-treating wastewater resulting from hydraulic fracturing includes filtration and phase separation by means of settling tanks. While physical separation of solid substances from the flowback is carried out through cyclonic separation with hydrocyclones at the production and injection wells, lightweight substances are skimmed off from the surface in the settling tanks.